Altogether 34 more 2-6-2+2-6-2 Double Prairie type narrow gauge locomotives were built, spread over five orders from three manufacturers over a span of 32 years.

However, in view of the fact that all the carrying wheels were fitted with roller bearing axle boxes and arranged as swiveling pony trucks, compared to the Class NG G13 of which the inner carrying wheels were built to the Gölsdorf system which allowed the axle some lateral movement, it was soon decided to reclassify them to Class NG G16.

They were mechanically similar to the earlier and subsequent Class NG G16 locomotives, but with a revised coal and water carrying arrangement.

[2] On the Avontuur Railway, these locomotives were used as tank-and-tender Garratts, but when the Langkloof members of the class were transferred to Natal in 1964, the water tenders were dispensed with since watering points were much closer together in Natal as a consequence of the early use of tank engines on those narrow-gauge branches.

Beyer-Peacock had stopped building steam locomotives after the last batch of Class NG G16 in 1958 and by 1968 they were in the process of closing the business altogether.

[2][4] After the Official Languages of the Union Act No 8 of 1925 was passed on 8 May 1925, bilingual English and Afrikaans cabside number plates began to appear on SAR locomotives, initially inscribed "SOUTH AFRICAN RAILWAYS" at the top and "SUID AFRIKANSE SPOORWEË" at the bottom.

[8] The Cockerill-built locomotives were delivered with bilingual cabside number plates inscribed "NG/G13" and with the older style Afrikaans "SUID AFRIKANSE SPOORWEË" at the bottom.

[1][2] The Beyer, Peacock locomotives ordered by the SAR, numbers NG109 to NG116 and NG125 to NG131, were shared more or less equally between the Natal and Langkloof lines.

[1][2] The seven Beyer, Peacock locomotives ordered by the Tsumeb Copper Corporation, numbers NG137 to NG143, were initially distributed between the Umzinto, Port Shepstone and Avontuur lines, but in 1964 the three that went to the Langkloof were also transferred to Natal.

NG141 achieved a fuel saving of 25% compared to a standard Class NG G16 Garratt, a performance which was easily maintained in regular service.

[9][10][11] Since withdrawal from SAR service, some locomotives were sold to foreign railways and into private hands and restored to operational condition, while others ended up in various degrees of preservation ranging across the spectrum from running order to staging to total abandonment.

[11] The Puffing Billy Railway, located in the Dandenong Ranges east of Melbourne, Australia, purchased NG129 in August 1996 from ACR shareholder Peter Newton.

From 2008 they have completely rebuilt it, including re-gauging it to 2 ft 6 in (762 mm) as additional capacity at a time of increasing passenger loadings.